How does a high stall converter work?

[xtreme80]

In a street truck with a mild to moderate 350 (350-400hp), how would, say, a 2500 stall converter work?

If I'm understand this right, it let's you apply the brake, then press down on the gas, and allow the engine to rev to around 2500 RPM so that when you let off the break you have a better launch off the line. I'm also thinking this is a very simple way to explain it.

Is this correct?

[gflo383]

your pretty much exactly right. the stall also depends on the amount of HP and TQ of the engine it is working with.

vewry similar to what you said, the stall speed is the highest RPM's the engine can rev to before the torque converter will engage the trans and tranfer the power to the rear wheels

a simple way to understand how a torque converter works: picture two household fans facing directly at one another. the one on the left is plugged in and on the highest speed, the one on the right is NOT plugged in, it gets its force or power to spin from the air moved by the left fan. only on a trans it works with fluid. the fan on the left that is plugged in is connected to the engine, and the one on the right with out being plugged in is connected to the input shaft of the transmission.

does that make sence?

also, i think a 2500 stall converter is a decent converter for a mild 350-400 horse engine. you just dont want to have a cruising speed below 2500 RPMS or you will burn up the trans due to it never stalling out. what gears do you have? i would recommend a 3.73 or higher with a stall converter at 2500.


a common stock converter stall is anywhere from 1300 to 1800 depending on the vehicle.

[gflo383]

also are you running a 4spd, 5 spd 5 spd, or auto, and with or with out OD? if you have an OD trans and a 3.73 rear gear, your cruise speed will be just below 2500 depending on your tire size. thats something else to consider....

hope i hepled and didnt confuse you at all.

[xtreme80]

Wow, made perfect sense!

Right now I have a TH350 with 2.73's in the rear. So I guess I wouldn't want to do this until I switched out rear end gears.

Thanks for all the information, and your analogy made perfect sense!

[gflo383]

with 2.73 at 60 mph you will be under your stall speed for sure.

and im gald i could help!

[piecesparts]

I run a 2400 stall convertor on my 84 GMC with a 770 R4 tranny, 3.73 gears, and a set of 27" tall tires on the truck. I have a stroked 383 motor in front of the tranny and with my setup the RPMs on the highway is at 2500 at 70 MPH and sllightly above at 80 MPH. When I am in the city, I shift down to DRIVE, so that I would not get into the OD and drop RPMs below the 2400. I have installed heavier duty tranny coolers ot assist in theremoval of heat generated by the slippage of the Torque convertor.

I did the 2400 stall to allow for the cam that I have in the 383 and let me drive in town easier.

[77-383 Step]

I'm not sure how they work but I had to replace the 2500 stall in my 500hp 383 with a 3200 stall. WOW,what a difference. Idles smoother, doesn't hesitate when you floor it at a stop. It totally woke the engine up. Got a 2500 with 100 miles on it...anyone?

[Srubydo1986]

I got a 2500 stall in my chevelle. after reading this i dont know, I think i should put a stock one back in.

Chevelle has about 400hp give or take. Engine is: a 350 bored.30 over with 69 corvetter heads and a high cam (unknow how high guy i got it from said its one down from highest you can get. He died before he could tell me for sheer). Transmission is a summit transmission th350 with manual valve body. Rear is a 3.08 will be 3.73.

Any ideas, sorry for high jack

[gflo383]

it all depends on the cam/heads intake. if the engine makes power from 1600 rpms, why would you want a stall converter? larger cam with a 108 LSA a terrible idle and a set of heads with a large 195cc intake runner and single plain intake that makes power from 2800 to 6500, a stall is a good idea.

if your looking to get a better launch off the line increase the stall by about 500 and you would be pleased as long as your engine isnt really wild.

[gflo383]

if you have a stall converter or stock, i would recommend an external trans cooler!!!

[piecesparts]

One decision factor in choosing a "Stall" convertor would be what is your car/truck doing at a stoplight. With a larger cam and the idle having to be upped slightly to make the engine stay running while in drive, you are probably a candidate for a stall convertor. Just a common sense thing to realize. The cam profile will make the engine run ragged at idle but when the tranny is engaged, then the engine is pulled down and you are holding the brake to keep it from pulling you through the stoplight. If you up the stall, then the tranny is not up against the idle RPMs and the motor can idle smoother. This will allow for a better power curve and when you accelerate, the engine will come up to speed, rather than be pulled down and just "STUMBLE" off of the line. When I upgraded to the 2400 from my 2200 stall, the engine came alive and the Mustangs learned to hate me.